using LEFT JOIN

[The Wanderer]

Hi People,

I have two tables which I am trying to perform a left join on.

table 1: master
columns | datatype
--------------------
masid | int(4)
maDesc | varchar(200)
maNote | varchar(200)

table 2: slave
columns | datatype
--------------------
asid | int(11)
masid | int(4)
uid | int(11)
cdate | datetime
title | text

my query is as follows

SELECT *
FROM `master`
LEFT JOIN `slave` ON master.masid = slave.masid
WHERE slave.uid = ? OR slave.uid IS NULL
ORDER BY master.masid DESC LIMIT 0, 30

I want to be able to display a row for each master.masid and then, depending
on whether a slave row exists that matches display a link to create on (this
is a php/mySQL project). Problem is it doesn't quite do what I want.

It only seems to return the one row with the highest master.masid if no
matching slave row exists for it, rather than listing all the masid rows for
which no matching slave row exists. It returns all the matching slave rows.

I understand that this may not be too clear, I just hope someone may be able
to help

Cheers,
Greg